Abstract: A wireless receiver for receiving signals from a satellite positioning system, and receiving signals from a communications system uses a common path in the receiver, and derives position information (60, 230) from the received signals by correlation (50, 210, 220) with a code. In a first mode the deriving is carried out from the received signals excluding selected signals received in time slots used for communications signals. A second mode includes such signals. This enables control of the trade off between accuracy and the latency of the positioning processor to improve the performance over a range of conditions. The mode input can be changed dynamically according to signal strength, or according to the needs of an application.

Abstract: A wireless receiver for receiving signals from a satellite positioning system, and receiving signals from a communications system uses a common path in the receiver, and derives position information (60, 230) from the received signals by correlation (50, 210, 220) with a code. In a first mode the deriving is carried out from the received signals excluding selected signals received in time slots used for communications signals. A second mode includes such signals. This enables control of the trade off between accuracy and the latency of the positioning processor to improve the performance over a range of conditions. The mode input can be changed dynamically according to signal strength, or according to the needs of an application.

Abstract: An antenna diversity receiver comprises a zero-IF receiver connected to two antennas (102a, 102b) via switches (532, 534). Simultaneous measurement of signal qualities from both antennas is possible by routing signals from the first antenna (102a) via a first mixer (106) and channel filter (116) and routing signals from the second antenna (102b) via a second mixer (108) and channel filter (118). A diversity controller (536) compares the signal qualities received from the antennas (102a, 102b) during a data preamble to select a preferred antenna, then adjusts the switches (532, 534) to route the signals from the preferred antenna to both input mixers (106, 108). The amplifier (104a, 104b) connected to the deselected antenna may be switched off during data reception, thereby minimizing extra power consumption. Such an antenna diversity receiver enables effective antenna selection to be performed, even in systems such as Bluetooth where only a very short preamble is provided for receiver configuration.

Abstract: A phase lock loop comprises a variable frequency oscillator (20), a divider (30), a phase comparator (40), a gain control stage (240), and a loop filter (50). The frequency response of the loop is measured by superimposing a modulation at a number of different rates on the error signal generated by the phase comparator, and by measuring for each modulation rate the peak-to-peak variation of the loop control signal controlling the oscillator frequency. If, due to errors in component values, the frequency response deviates from its desired value, the loop gain is adjusted to bring the frequency response close to its desired value.

Abstract: A slave radio transceiver for use in a frequency hopping radio system synchronizes by receiving on a sequence of simultaneous combinations of radio channels until a paging message is received from a master transceiver, and may then revert to single channel frequency hopping operation. The slave's multi-channel receiver is sub-equipped to receive simultaneously on a only sub-set (PF12, PF13) of the channels within its bandwidth, the received channels being selected by independent programming within the bandwidth. The channels received simultaneously may be selected to correspond to different degrees of misalignment between the master and slave.

Abstract: An antenna diversity arrangement is applicable to frequency hopping receiver (34) for receiving data packets transmitted on frequency channels lying within an overall frequency bandwidth, divided into a plurality of sub-bands. In each sub-band the frequency characteristics of the channel will be substantially the same. The choice of antenna (10, 12) for a particular sub-band is done by carrying-out frequency diversity measurements and the selection is treated as being valid for a period of time which may be preset or determined dynamically. In operation the hopping sequence is known to the receiver so that it can determine in advance the frequency of the next data packet to be received and can select the particular antenna without the necessity of carrying out diversity measurements. At the end of the time period the suitability of the selected antenna is checked and if necessary the selection is updated in the receiver.

Abstract: An antenna diversity receiver comprises a zero-IF receiver connected to two antennas (102a, 102b) via switches (532,534). Simultaneous measurement of signal qualities from both antennas is possible by routing signals from the first antenna (102a) via a first mixer (106) and channel filter (116) and routing signals from the second antenna (102b) via a second mixer (108) and channel filter (118). A diversity controller (536) compares the signal qualities received from the antennas (102a,102b) during a data preamble to select a preferred antenna, then adjusts the switches (532,534) to route the signals from the preferred antenna to both input mixers (106,108). The amplifier (104a,104b) connected to the deselected antenna may be switched off during data reception, thereby minimizing extra power consumption. Such an antenna diversity receiver enables effective antenna selection to be performed, even in systems such as Bluetooth where only a very short preamble is provided for receiver configuration.

Abstract: A tuneable filter, for example an antenna filter in a single chip radio receiver, comprises a frequency selective circuit (12) including passive reactive components. At least some of the reactive components (48 to 52) are arranged as a bank (46 ) which includes switches (53 to 57) for switching at least one of the reactive components in the bank into the frequency selective circuit. A controller controls the switching means to select the or a combination of the reactive components which provides an optimum sensitivity for an input signal at a first frequency. The switch settings required to optimise the sensitivity for other frequencies is determined by measuring the decrease in sensitivity for other switch settings, with the input signal still at the first frequency, and using stored data about the shape of the frequency response of the tuneable filter.

Abstract: A tuneable filter, for example an antenna filter in a single chip radio receiver, comprises a frequency selective circuit (12) including passive reactive components. At least some of the reactive components (48 to 52) are arranged as a bank (46 ) which includes switches (53 to 57) for switching at least one of the reactive components in the bank into the frequency selective circuit. A controller controls the switching means to select the or a combination of the reactive components which provides an optimum sensitivity for an input signal at a first frequency. The switch settings required to optimise the sensitivity for other frequencies is determined by measuring the decrease in sensitivity for other switch settings, with the input signal still at the first frequency, and using stored data about the shape of the frequency response of the tuneable filter.

Abstract: An antenna diversity arrangement is applicable to frequency hopping receiver (34) for receiving data packets transmitted on frequency channels lying within an overall frequency bandwidth, divided into a plurality of sub-bands. In each sub-band the frequency characteristics of the channel will be substantially the same. The choice of antenna (10, 12) for a particular sub-band is done by carrying-out frequency diversity measurements and the selection is treated as being valid for a period of time which may be preset or determined dynamically. In operation the hopping sequence is known to the receiver so that it can determine in advance the frequency of the next data packet to be received and can select the particular antenna without the necessity of carrying out diversity measurements. At the end of the time period the suitability of the selected antenna is checked and if necessary the selection is updated in the receiver.

Abstract: A slave radio transceiver for use in a frequency hopping radio system synchronises by receiving on a sequence of simultaneous combinations of radio channels until a paging message is received from a master transceiver, and may then revert to single channel frequency hopping operation. The slave's multi-channel receiver is sub-equipped to receive simultaneously on a only sub-set (PF12, PF13) of the channels within its bandwidth, the received channels being selected by independent programming within the bandwidth. The channels received simultaneously may be selected to correspond to different degrees of misalignment between the master and slave.

Abstract: An antenna diversity receiver comprises a zero-IF receiver connected to two antennas (102a, 102b) via switches (532,534). Simultaneous measurement of signal qualities from both antennas is possible by routing signals from the first antenna (102a) via a first mixer (106) and channel filter (116) and routing signals from the second antenna (102b) via a second mixer (108) and channel filter (118). A diversity controller (536) compares the signal qualities received from the antennas (102a,102b) during a data preamble to select a preferred antenna, then adjusts the switches (532,534) to route the signals from the preferred antenna to both input mixers (106,108). The amplifier (104a,104b) connected to the deselected antenna may be switched off during data reception, thereby minimizing extra power consumption.